This proposal, which is an extension of an interdisciplinary study already in progress, will examine the hypothesis that ambulatory blood pressure (BP) is importantly influenced by behavioral stimuli (particularly those associated with the work environment) and personality characteristics, and that the resultant different patterns of BP have discernably different consequences with regard to target organ damage. The first two studies will be designed to compare the reliability of ambulatory recordings using portable noninvasive recorders with other BP measures. In study A, two recordings will be made 2 weeks apart in 20 patients, both on working days. Study B will be similar except that one recording will be on a working day, and one on a non-working day. In study C 300 white males with normal or untreated but mildly elevated BP will be recruited from two populations, one largely professional, and one largely blue collar. Twenty-four hour ambulatory BP recordings will be made on a working day and correlated with a wide variety of independent variables including activity and mood during the recording, sociodemographic, nutritional, physiological/biochemical, occupational (which includes the Karasek occupational stress profile), and psychometric tests. Subjects will also perform 3 standardized stress tests in the laboratory (1 physical and 2 mental) to see whether there is a correlation between laboratory and real life stress. BP will be measured in 4 ways: (a) ambulatory 24 hr. recording, (b) conventional clinic recordings, (c)\home readings taken by the patient, and (d) changes during the stress testing. Target organ damage will be a dependent variable and be assessed in the heart by echocardiography and in the kidney by the urinary excretion of an enzyme (NAG) which is a sensitive marker of hypertension-induced renal damage. Specific objectives will include: 1) Comparison of the reproducibility of different measures of BP (ambulatory versus clinic versus home); 2) to determine which measures of BP correlate best with target organ damage; 3) to assess the influence of behavioral and psychosocial influences on BP; 4) to test the hypothesis that subjects in "high strain" occupations (assessed on the Karasek scale) will have the highest BP during work; and 5) to assess whether BP variability is correlated with target organ damage independently of the average BP level.